Color mixing lighting apparatus



Aug- 17 1954 R. G. WILLIAMS 2,686,866

COLOR MIXING LIGHTING APPARATUS RULLO G/LEsP/E w/LL/AMS BY Aw@ M4 19%;

Aug. 17, 1954 R. G. WILLIAMS 2,686,866

coLoR MIXING LIGHTING APPARATUS Filed Dec. zo, 1949 2 sheets-sneer 2 /3-.lmlllfllu INVENTOR. ROL/.0 G/LLESP/E W/LL/AMS ATTORNEYS Patented ug.17, 1954 2,686,866 COLOR MIXING LIGHTING APPARATUSy Rollo GillespieWilliams,

signor, by mesne assi Corporation, North Be of New York Great Neck, N.Y., asgnments, to Duro-Test rgell, N J., a corporation ApplicationDecember 20, 1949, Serial N o. 133.992

(Ci. 24o-3.1)

Claims.

This invention relates to color mixing lighting apparatus and hasparticular but not exclusive reference to spotlights.

An object of the invention is to enable a number of light beams ofditferent colors or a number of light sources each giving a light ofdierent vcolor to provide illumination which can be blended into onennal beam of light of resultant color.

It is sometimes desired to mingle the light of a plurality of colorssuch for example as the four colors, white, red, green, and blue, insuch a manner that by blending the lights in different proportionsdifferent color hues are obtained. If four spotlights corresponding tothese four colors are mounted close together, it will be found thatundesirable color shadows are created and the four beams do notgenerally intermingle sufficiently to avoid what is known as colorfringing.

t is therefore desired that these beams should be so intermingled thatthe colors in question can be suiiciently combined to avoid thesephenomena, and an object of the present invention is to provide a simplebut effective apparatus whereby this result may be achieved. It is to beunderstood, however, that this invention applies to the combination ofany required number of colored light sources, and that the number fouris quoted merely as an example. Also the source can be arranged to giveany desired color of light and means may be employed for varying thecolor and/or intensity of the useful emitted blended light. For example,in the case of a plurality of light sources, individual dimmers may beemployed to vary the useful emitted light.

Other specific objects of the invention are to provide means for mixingcolored lights which are simple in construction and design, arecomparatively inexpensive to make, are compact and comparatively smallin size, are easily and readily maintenanced and are possessed of a highdegree of lighting enciency.

Another object is to provide a light transmission system consisting ofat least two light reiiecting systems so arranged and designed that apredetermined proportion of emitted light is transmitted independentlyof said system and the remainder is reliected from the rst to thelsecond system and from such latter system is transmitted in-substantial parallel -spaced relation to the independently transmittedlight.

A more specic object of the invention is to provide a light transmitterconsisting of at least two truncated conical, pyramidal Vor the likerefleeting Surfaces. disposed in an Opposed Sense about .a Substantiallycommon axis with their bases remote from each other; the two truncatedVconical reflecting surfaces may be the same as or different from oneanother as desired; they rnay be symmetrical or asymmetrical and, as acone is mathematically that special form of pyramid having an innitenumber of sides, the expression truncated pyramidal reflecting surfaceas used herein where the context s o permits, means and includes amulti-sided member having the general outline of a truncated cone. Inparticular, one of the reecting surfaces may be constituted by a singlesurface (conical) and the other is constituted by a plurality ofsurfaces (pyramidal).

More specifically the invention has for an object the provision of aplurality of light sources, means for transmitting different coloredlight from or via each or selected thereof, at least two reflectingsystems, the lecting a proportion of the emitted light from at least oneof said sources on to the other system and said latter system reectingsaid renected light in substantial parallelism and in spaced relation tolthe remaining proportion of the emitted light kfrom said'source.

In the alternative ar single light source may be employed and means areprovided whereby two or more substantially parallel light beams ofdifferent color or hue are obtained from said' single source and aproportion of one or more of said beams is/,are app-lied to saidreecting systems manner set out above.

`It is another object to provide special -rneans for insuring that theemitted light which -is transmitted independently of said reflectorsystem is con-lined to mainly parallel rays of light, and to that endLit is another object to provide louvres or shields so located relativeto the light source or each light source that such independent light istransmi-ttedfmainly as parallel rays.

n carrying the invention into effect the two reflecting systems may bespaced from one another or .otherwise as desi-red, but in the latterevent they are preferably connected by an opaque connection. Thereecting surface of .each `or either system may be ribbed, flutted,smooth, indented .or irregular. The `reecting systems or either :thereofmay include a transparent ypart .or parts for the non-reected light.

The Iinvention Acontemplates -both the provision of a .complete lightingsystem for transmitting light` and a transmitter for use with a lightingsystem.

one of said systems re- Other objects will become apparent from thefollowing description taken in connection with the attached drawingsshowing several illustrative embodiments of the invention and wherein:

Fig. 1 is a horizontal cross-sectional view along the axis I-I of Fig. 2illustrating by way of example one form of the spot light in which theinvention is embodied, the view in Fig. 1 omitting one of the lampsshown in Fig. 2 to avoid confusion in the drawing;

Fig. 2 is a vertical end view of the spot-light shown in Fig. 1;

Fig. 3 is a perspective view of one type of reflector in accordance withthis invention;

Fig. 4 is a horizontal cross-sectional view along the axis 4-4 of Fig. 5showing a modified form of the invention in Fig. 1 showing the use oflouvres positioned in front of the light sources;

Fig. 5 is a vertical end view of the form of Fig. 4; and

Figs. 6, '7, 8, and 9 are views similar to Fig. l showing furthermodified forms of the invention.

In the embodiment illustrated there are four sources of light, R, W, B,and G, each of which may be an electric lamp bulbi. It will beappreciated that any suitable source of light may be employed andreflector spot lamps have been found to be suitable.

Each lamp is supported by a lamp holder i and the lamps are arrangedconcentrically equally spaced from one another. The lamp holders l may-be located interiorly of a suitable casing indicated generally at 2which may be provided with any convenient means for mounting orattaching it to any desired support. Disposed at a convenient positionbelow the bulbs R, G, and B, is a color lter 3. In the particularembodiment under discussion it will be assumed that lamp R will emit(through its associated filter) a red beam, lamp G a green beam, lamp Ba blue beam and lamp W a white beam but it will be obvious that anydesired color or colors may be obtained and the number of differentcolored beams emitted can be varied as desired. Furthermore, instead ofusing lters, the lamps themselves may emit light of the desired color.

In a still further alternative, parallel spaced beams of differentlycolored light are obtained from a single source by any convenient meanssuch as the use of prisms and filters.

Reverting to the embodiment of the invention illustrated in Figs. l to3, it will be seen that at a convenient distance below the filters 3 arelocated two truncated hollow cones 4 and 5 which are similar andsymmetrical and have a common axis; they are arranged in an oppositesense with their bases remote from one another and with their other endsin contact with each other. The interior surfaces of members 4 and 5 arereflecting surfaces. The cones may, for example, be made of anodisedaluminum but they may be made of any other suitable material providedtheyt have a good reflecting surface.

Itnwill be readily seen from Fig. 1 that each lamp is so disopsed inrelation to the cones that a proportion of the emitted light passesthrough the aperture at the junction of the cones without impinging onany of the interior` surfaces of the cones and that the remainder of thelight impinges upon the interior surface of the upper cone 4, from thereis reflected more or less diametrically to the interior surface of thelower cone 5 and from such latter surface is reflected `more or lessparallel to and in spaced relation with the light which passes throughthe cones without impinging upon any surface thereof.

For the purpose of convenience the light rays from lamps B and R onlyare shown on the drawing but it will be appreciated that the sameconditions will apply to the rays emitted from all the lamps. The raysfrom lamps B and R which pass the cones without impinging upon any ofthe surfaces thereof are indicated at B1 and R1 and the remaining raysare indicated at Bz and R2.

An approximation of the reflecting surface area from which the rays B2are reflected from the lower cone 5 is indicated at B in Fig. 2 and itwill be seen that that area is considerably greater than the area B4from which the light rays Bi are emitted. This, as will readily beappreciated results in very efiicient mixing of the colors. It will beappreciated that cones 4 and 5 are securely xed within the casing 2 byany suitable and convenient means.

Referring now more particularly to the modied form shown in Figs. 4 and5, it has been discovered that there may be a tendency for light tospill from each filter; that is to say there is a tendency for lightrays to be emitted in the direction of the arrows X. In so far asconcerns the rays which impinge upon the cones, the spilled lightimpinges upon the casing 2 and can be ignored but in so far as concernsthe independent light, the rays X moving to the left from bulb B (inFigure 4) will intermingle with the rays X moving to the right from bulbR and in order to avoid this spilling (which, of course, occurs at allpoints of emission of the independent light) and the consequentialdiffusion arcuate louvres or shields 6 are provided as shown. There areconveniently a series of concentric louvres the lengths of which arestepped as shown, those furthest fromthe center being of greater lengthand extending to a position beyond the upper edge of cone 4. lThelouvres may be of any suitable material and are preferably opaque tolight and extend parallel to one another and to the axes of the cones.It thus follows that any spilling of the independent light is positivelyprevented.

The lamp bulbs may be of any suitable type as, for example, of thereflector type and for the purpose of compactness may be of low voltage(e. g. 6 or 12 volts). It may be said that reflector type bulbs comprisea glass or other suitable bulb which is externally prepared as areflector and silvered or similarly treated on the interior surface.

It will be noted that in the forms shown in Figs. 1 to 5, inclusive,those portions of the several light beams which bypass the reflectorspass through the aperture in the reiiectors. Fig. 6 shows a modied formin which that portion of the several beams of light which bypass thereectors pass on the outside of the reflectors 4b and 5b, This providesa similar scrambling or mixing of the light beams of different colors.In this form the reflectors are supported from the casing by means ofarms I3. It will be noted that the light sources i I and l2 are enclosedin reiiectors lla and 12a, respectively, these reflectors being ofparabolic or other similar cross-section to parallelize the rays.

Fig. 7 shows a form similar to that of Fig. 6 except that the coloredglass plates 3 are made larger and arranged as close together aspossible so that the beams of each color are split into three portions,one of which passes directly through the apertures in the reectors 4cand 5c, a. second portion is reflected from reflector 4c to and from thereflector 5c and the third portion of each beam passes outside of thereectors. It Will be noted that with this form of the invention eachbeam is split into three parts so that if four light sources are used,twelve beams of various colors are emitted, and that these beams arethoroughly mixed or scrambled.

Fig. 8 shows another form of the invention using a fairly small reector4d and a larger reflector 5d, they being so arranged that one portion ofeach beam passes between the reiiectors whereas the balance of each beamis reected from reflector 4d onto and from reector 5d.

Fig. 9 shows a form of construction similar to that of Fig. 8, thedifference being that the members 3 are made larger and located as closetogether as possible so that each beam is split into three parts, onepart passing through the center of reflectors 4e and 5e, another portionis reflected the third portion is emitted directly exteriorly ofreflector 4e and interiorly of reiiector 5e. This again splits each beaminto three portions in scrambled or interspersed relation to portions ofthe beams of other colors.

It will be appreciated that a color mixer in accordance with thisinvention can be produced comparatively inexpensively, is comparativelyrobust and has the further advantage that maintenance costs are verysmall.

While in some of the forms illustrated the beams of light of differentcolors are shown as coming from individual light sources, it will befrom a single light source. One form of construction for accomplishingthis is shown, for example, in Fig. 7 of my Patent No. 2,673,923, issuedMarch 30, 1954, to which reference is made.

It will be noted that the constructions shown and described will serveadmirably to accomplish the objects stated above. It is to beunderstood, however, that the constructions disclosed above are intendedmerely as illustrative of the invention and not as limiting as variousmodifications therein may be made Without departing from the inventionas dened by the claims which follow.

I claim:

1. In color mixing lighting apparatus, means for emitting discrete lightbeams of a plurality of diierent colors, a centrally perforatedreiiector mounted adjacent said emitting means having a larger endnearest said emitting means and so located that a portion of each beamis emitted through the central opening in said reector, and a secondcentrally perforated reflector mounted coaxially with said firstreflector and further from said light beam emitting means, and havingits smaller end adjacent to the smaller end of the iirst mentionedreflector, the said reflectors being so formed that the balance of eachbeam impinges on said first mentioned reiiector, is reilected therefromonto the second reflector and is retherewith the directly emittedportion of the respective beam.

2. In color mixing lighting apparatus, means for emitting a plurality ofintegral light beams of different color, a reiiector of truncatedpyramidal form mounted adjacent said light beams with its larger endnearest said emitting means and so located that a portion of each beamis emitted through the opening in said reflector, and a secondreflectorv of truncated pyramidal form end adjacent to the smaller endof the rst mentioned reflector, the said reflectors being so formed thatthe balance of each beam impinges on said rst mentioned reflector, isreflected therefrom onto the second reector and is reflected from saidsecond reflector in a direction substantially parallel to withoutintermingling therewith the directly emitted portion of the severalbeams.

3. In color mixing lighting apparatus, means for emitting spacedparallel light beams of a plurality of visibly different colors, areflector of truncated-conical form mounted adjacent said light beamemitting means with its larger end nearest said emitting means and withits axis substantially parallel to and equally spaced from said lightbeams and so located that a portion of each beam is emitted through theopening in said reector, and a second reiiector of truncatedconical formmounted coaxially with said rst reector and further from said light beamemitting means, and with its smaller end adjacent to the smaller end ofthe rst mentioned reflector, the said reiiectors being so formed thatthe balance of each beam impinges on said first mentioned reector, isreiiected therefrom onto the second reiiector and is reiiected from saidsecond reflector in a direction substantially parallel to the directlyemitted portion oi' the several beams.

4. The combination according to claim 1 in which means are provided toensure that that portion of each beam which is emitted through theopening in the first reflector is emitted only as substantially parallelrays.

5. The combination according to claim 1 in which means are provided toensure that that portion of each beam which is emitted through theopening in the rst reflector is emitted only as substantially parallelrays, said means comprising concentrically arranged light guides.

6. In color mixing lighting apparatus, means portion bypasses saidreiiector, and a second reector of truncated-pyramidal form mountedfurther from said light beam emitting means, the said reflectors beingso formed and arranged that the portions of said beam which impinge onsaid rst mentioned reliector are reflected therefrom onto the secondreflector portions of the said beams.

7. In color mixing lighting apparatus, means said emitting means and solocated that a portion of each beam bypasses said reflector, and asecond reiector of truncated-pyramidal form mounted coaxially with saidfirst reflector and further from said light beam emitting means, andwith its smaller end toward the smaller end of the rst mentionedreector, the said reectors being so formed and mounted that a portion ofeach beam may pass through apertures at the center of said reiiectors,that another portion 7 may pass exteriorly of at least one of saidreflectors and that the balance of each beam impinges on said firstmentioned reflector, is re- I flected therefrom onto the secondreflector and is reflected from said second reflector in a directionsubstantially parallel to the directly emitted portions of the saidbeams.

8. In color mixing lighting apparatus, means for emitting spaced lightbeams of a plurality of visibly different colors, a reflector oftruncatedpyramidal form mounted adjacent said light beam emitting meansWith its larger end nearest said emitting means and so located that aportion of each beam bypasses said reflector, and a second reector oftruncated-pyramidal form mounted coaxially with said first reflector andfurther from said light beam emitting means, and with its smaller endtoward the smaller end of the first mentioned reflector, the saidreflectors being so formed and mounted that a portion of each beam maypass exteriorly of both of said reflectors and that the balance of eachbeam impinges on said first mentioned reflector, is reflected therefromonto the second reflector and is reflected from said second reector in adirection substantially parallel to the directly emitted portions of thesaid beams.

9. In color mixing lighting apparatus, means for emitting spaced lightbeams of a plurality of visibly different colors, a reflector oftruncatedpyramidal form mounted adjacent said light beam emitting meanswith its larger end nearest said emitting means and so located that aportion of each beam bypasses said reflector, and a second reflector oftruncated-pyramidal form mounted coaxially With said first reflector andfurther from said light beam emitting means, and with its smaller endtoward the smaller end of the first mentioned reflector, the saidreflectors being so formed and mounted that a portion of each beam maypass exterlorly of one of said reflectors and interiorly of the otherreflector and that the balance of each beam impinges on said firstmentioned reflector, is reflected therefrom onto the second reflectorand is reflected from said second reflector in a direction substantiallyparallel to the directly emitted portions of the said beams.

l0. In color mixing lighting apparatus, means for emitting spaced lightbeams of a plurality of visibly different colors, a reflector oftruncatedpyramidal form mounted adjacent said light beam emitting meanswith its larger end nearest said emitting means and so located that aportion of each beam bypasses said reflector, and a second reflector oftruncated-pyramidal form mounted coaxially with said first reflector andfurther from said light beam emitting means, and With its smaller endtoward the smaller end of the rst mentioned reflector, the saidreflectors being so formed and mounted that a portion of each beam maypass through apertures at the center of said reflectors, that anotherportion may pass exteriorly of one of said reflectors and interiorly ofthe other reflector and that the balance of each beam impinges on saidfirst mentioned reflector, is reflected therefrom onto the secondreflector and is reflected from said second reflector in a directionsubstantially parallel to the directly emitted portion of the saidbeams.

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